What is it?
An empyema is infection in the pleural space. The pleural space
is the potential space between
the lung and the chest wall. The development of an empyema results
from fluid within the pleural
space which becomes infected, and the deposition of infected protein
material onto the surface of
the lung and the chest wall. The infected material deposited onto
the lung is called a pleural peel.

The pleural space normally has a moist surface, allowing the expanding
and contracting lung to
slide smoothly over the inside of the chest wall. Under normal circumstances,
there is no
significant amount of fluid, and there is no air, in the pleural
space. The lung is normally
completely expanded inside the chest. When an empyema is present,
the lung is compressed by
the fluid in the pleural space, and the lung becomes "trapped"
within the material, unable to fully
inflate. The patient may be very short of breath, and typically
has a high fever and feels very
sick.

What causes it?
Most empyemas begin as a pneumonia. Some patients with pneumonia
develop a pleural effusion.
(Please see the related article on pleural effusion.) In most patients,
the pleural effusion resolves
when the pneumonia is treated. For unknown reasons, in some patients,
the effusion does not go
away, but becomes infected. An infected pleural effusion is called
an empyema. The empyema
has two components: the fluid in the space, and the pleural peel
deposited onto the lung and
chest wall. The vast majority of empyemas will not respond to antibiotics,
nor will they resolve
on their own. The vast majority require surgical exploration and
drainage.

The remaining causes of empyema are secondary infections of a bland
pleural effusion. For
example, a patient with heart failure may develop a pleural effusion.
The same patient may
develop a urinary tract infection. Bacteria from the urinary tract
infection enter the blood, and
then infect the pleural effusion, resulting in an empyema.

A relatively rare cause of empyema in the United States is tuberculosis.
Tuberculous empyemas
are associated with pulmonary tuberculosis.

How is it treated?
In the presence of pneumonia, the foundation of the treatment of
empyema is antibiotic therapy
of the pneumonia. In concert with the antibiotics, the infected
fluid must be drained, and the
pleural peel must be removed from the lung and chest wall.

If the process is discovered early, then a minimally invasive thoracoscopy
(VATS) procedure may
be used. (Please see the related article on Thoracoscopy elsewhere
in this site.) Through tiny
incisions, under endoscopic guidance, the fluid is drained and the
pleural peel is removed from
the surface of the lung and chest wall. Two or three drains called
chest tubes are left in the
pleural space. They are usually removed 4 to 7 days after surgery.

If the process is discovered later, and the amount and density of
the pleural peel exceeds the
ability of thoracoscopy to remove it, then a thoracotomy is required.
(Please see the related
article on Thoracotomy elsewhere in this site.) At the time of thoracotomy,
a five or six inch
incision is made on the chest wall, and the chest is entered. The
infected fluid is removed and is
sent for analysis. The pleural peel is carefully removed from the
lung and from the chest wall.
The lung is fully re-expanded. Several drains are placed, and remain
in place for 4 to 7 days.